There is actually more the calculus than that. Not only do you have to know the airplane, be able to teach, but you have to be willing to live in ATL. With no more positive space, per diem and hotels, the 747 fleet is losing a huge number of DGS instructors, many of which literally wrote the original training program. Replacing all of them means you might have to make compromises.

From the fleet directors perspective, they like junior instructors because it helps out their budget in the "get paid what you can hold" scale. I would hazard a guess to say that there are other fleets that do the same thing, just not as high profile.

They are hiring more instructors, if you know the airplane, apply.